<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>箭头函数</title>
</head>
<body>
    <script>
        function a(method){
            console.log("开始执行..")
            method()
            console.log("结束执行..")
        }

        function test(){
            console.log("123")
        }

        a(test)
        a(function (){
            console.log("456")
        })
        a(() => {
            console.log("789")
        })
    </script>
</body>
</html>